改性聚乙烯醇纤维增强水泥基复合材料制备及其力学性能

为提高聚乙烯醇(PVA)纤维与水泥基体间的界面强度,采用化学接枝法在PVA纤维表面接枝一层纳米二氧化硅颗粒(SiO₂ NPs),制备改性PVA纤维增强水泥基复合材料(PVA-FRCC)。通过三点弯曲试验测试改性前后PVA-FRCC的抗弯强度,并研究纤维铺排方向和层数对水泥基复合材料抗弯性能的影响。结果表明:纤维交叉铺排时,PVA-FRCC的抗弯强度优于纵向和横向铺排,且改性PVA-FRCC的抗弯强度高于未改性PVA-FRCC的;当纤维铺排层数为3层时,改性PVA-FRCC的抗弯强度最好。对PVA-FRCC的弯曲过程进行有限元模拟分析,含有横向铺排纤维的PVA-FRCC断裂失效时,纤维的桥连作用突显。同时,交叉铺排的PVA-FRCC中除横向铺排的纤维承力外,纵向纤维也有一定的承力,且试样失效后无界面损伤。

Preparation and mechanical properties of cementitious composites reinforced by modified polyvinyl alcohol fiber

In order to improve the interface bonding strength between polyvinyl alcohol (PVA)fiber and cement, silica nanoparticles (SiO₂ NPs) were grafted on the surface of PVA fiber to prepare modified PVA fiber reinforced cementitious composites (PVA-FRCC). The bending strength of PVA-FRCC was evaluated by three-point bending test, and the influences of fiber arrangement direction and layer number on the bending strength were studied. The results show that the bending strength of PVA-FRCC with cross arrangement is better than that of longitudinal or transverse arrangement. The bending strength of composite reinforced by modified PVA fiber is higher than that with unmodified fiber. The bending strength of modified PVA-FRCC is the best when the number of fiber layers is 3. In the finite element analysis of bending process, when the failure occurs, the transverse fibers in PVA-FRCC present an obvious bridging function. Meanwhile, the longitudinal fibers in the cross-arranged PVA-FRCC could bear a low load while the transverse arranged fibers bear the main load and show no interface damage after failure.